Can lo and Europa Support Life?
Some scientists think that two of Jupiter’s four large (“Galilean”) moons, lo and Europa, may be candidates for hosting life-in part because both of them have two important preconditions, water and an energy source. lo is similar to the rocky inner planets (such as Earth and Mars) in its composition, having an iron core and large amounts of silicon. Proximity to Jupiter makes it far more geologically dynamic than any other planet or moon. Tidal forces- caused by the gravitational effects of Jupiter and other moons-deform lo as it passes through its orbit. The process heats the moon, and constant volcanism results as the surface crust fails to keep in the sloshing magma (liquefied rock) underneath. The surface can change up to a hundred meters between high and low tide in some places. Other than Earth, lo is the only object in the solar system known to have currently active volcanoes. Eruptions wipe out all evidence of meteoric impacts; no craters can be seen on the surface.
lo seems, however, to have too much energy to make a good habitat for life. In addition to volcanism, the moon gets energy from the intense magnetic field of Jupiter. As the moon passes through this field, tremendous amounts of energy are generated. The forces strip nearly a ton of mass from the surface every second, creating a cloud of charged ions around the moon. Life as we know it would quickly dissolve on the surface of lo.
The second nearest of the Galilean satellites is Europa. In many respects it resembles lo, but its composition is radically different. Europa possesses large quantities of water, either as ice or as a liquid. Massive tides warm Europa, though they are only about one-tenth as strong as the ones affecting lo. On this moon, the tides probably maintain an extensive ocean under the sea ice. Several lines of evidence point to liquid water. Planetary scientists were surprised to discover that very few large craters exist on the surface. Some process must be resurfacing the planet on a regular basis, leading many to believe that liquid water spills out. Second, the Galileo spacecraft detected a magnetic field induced by Jupiter. Some conducting material must be present around the inside of the planet. Liquid water with salts seems the most likely solution. Finally, the mass and size of Europa are consistent with an ice-and-water mixture.
Unfortunately, Europa exploration will prove difficult. Engineers are working on plans to reach the subsurface ocean, but currently there are no workable plans to place a drill on the surface that could tunnel through many kilometers of ice. Looking at all the evidence, planetary scientists believe that Europa consists of a rocky core accounting for less than one-half its depth. Over this core rest many kilometers of liquid water and ice. Different models give different depths of surface ice over the ocean, and further studies of composition, salinity, and surface features will certainly lead to a better understanding, but a large saltwater ocean seems probable. Tidal forces from interactions with Jupiter and other moons would keep the water liquid despite the subfreezing exterior temperature of -170° Celsius. Craters would be eliminated whenever meteors pierced the surface ice or tidal forces formed giant cracks. Saltwater from underneath would spread out and freeze, making a new top layer in the area around the event.
The importance of liquid water to life causes astrobiologists to be very excited about Europa. Liquid water appears to be rare other than on Earth, but here we have an ocean of it. Nonetheless, a number of other considerations are important. Carbon might not be difficult to find, as long as some form of internal circulation rotates heavier metals from the rocky core out into the water. Energy might be more difficult, though. Solar radiation hits the icy surface where life is unlikely to survive. Energy would have to be generated from some other source under the ice, possibly volcanic or magnetic processes. Some astrobiologists believe that Europa could have magma vents (surface openings through which materials escape) like the deep-sea vents at the midoceanic ridges on Earth. Such vents could provide both carbon and energy for an ecosystem.
1
Some scientists think that two of Jupiter’s four large (“Galilean”) moons, lo and Europa, may be candidates for hosting life-in part because both of them have two important preconditions, water and an energy source. lo is similar to the rocky inner planets (such as Earth and Mars) in its composition, having an iron core and large amounts of silicon. Proximity to Jupiter makes it far more geologically dynamic than any other planet or moon. Tidal forces- caused by the gravitational effects of Jupiter and other moons-deform lo as it passes through its orbit. The process heats the moon, and constant volcanism results as the surface crust fails to keep in the sloshing magma (liquefied rock) underneath. The surface can change up to a hundred meters between high and low tide in some places. Other than Earth, lo is the only object in the solar system known to have currently active volcanoes. Eruptions wipe out all evidence of meteoric impacts; no craters can be seen on the surface.
The word “Proximity” in the passage is closest in meaning to
ACloseness
BAttraction
CSimilarity
DSuperiority
2
Some scientists think that two of Jupiter’s four large (“Galilean”) moons, lo and Europa, may be candidates for hosting life-in part because both of them have two important preconditions, water and an energy source. lo is similar to the rocky inner planets (such as Earth and Mars) in its composition, having an iron core and large amounts of silicon. Proximity to Jupiter makes it far more geologically dynamic than any other planet or moon. Tidal forces- caused by the gravitational effects of Jupiter and other moons-deform lo as it passes through its orbit. The process heats the moon, and constant volcanism results as the surface crust fails to keep in the sloshing magma (liquefied rock) underneath. The surface can change up to a hundred meters between high and low tide in some places. Other than Earth, lo is the only object in the solar system known to have currently active volcanoes. Eruptions wipe out all evidence of meteoric impacts; no craters can be seen on the surface.
According to paragraph 1, which of the following statements is true about lo, Mars, and Earth?
AThey all have active volcanoes.
BThey have similar tidal forces.
CThey are equally geologically dynamic.
DThey are made up of the same elements.
3
lo seems, however, to have too much energy to make a good habitat for life. In addition to volcanism, the moon gets energy from the intense magnetic field of Jupiter. As the moon passes through this field, tremendous amounts of energy are generated. The forces strip nearly a ton of mass from the surface every second, creating a cloud of charged ions around the moon. Life as we know it would quickly dissolve on the surface of lo.
The word “intense” in the passage is closest in meaning to
Alarge
Bstrong
Csurrounding
Dconstant
4
lo seems, however, to have too much energy to make a good habitat for life. In addition to volcanism, the moon gets energy from the intense magnetic field of Jupiter. As the moon passes through this field, tremendous amounts of energy are generated. The forces strip nearly a ton of mass from the surface every second, creating a cloud of charged ions around the moon. Life as we know it would quickly dissolve on the surface of lo.
According to paragraph 2. which of the following is explained by lo’s passage through Jupiter’s magnetic field?
AThe nature and extent of lo’s volcanism
BThe speed at which lo orbits Jupiter
CThe composition of lo’s surface crust
DThe presence of a cloud of charged ions around lo
5
The second nearest of the Galilean satellites is Europa. In many respects it resembles lo, but its composition is radically different. Europa possesses large quantities of water, either as ice or as a liquid. Massive tides warm Europa, though they are only about one-tenth as strong as the ones affecting lo. On this moon, the tides probably maintain an extensive ocean under the sea ice. Several lines of evidence point to liquid water. Planetary scientists were surprised to discover that very few large craters exist on the surface. Some process must be resurfacing the planet on a regular basis, leading many to believe that liquid water spills out. Second, the Galileo spacecraft detected a magnetic field induced by Jupiter. Some conducting material must be present around the inside of the planet. Liquid water with salts seems the most likely solution. Finally, the mass and size of Europa are consistent with an ice-and-water mixture.
Which of the following can be inferred from paragraph 3 about the presence of life on Europa?
ALife on Europa would be more likely if a conductive material like salt were present in the water.
BJupiter’s magnetic field may be too strong to support life on Europa.
CEuropa is more likely than lo to be capable of supporting life
DAny life on Europa would likely be found on its surface, not in its ocean.
6
Unfortunately, Europa exploration will prove difficult. Engineers are working on plans to reach the subsurface ocean, but currently there are no workable plans to place a drill on the surface that could tunnel through many kilometers of ice. Looking at all the evidence, planetary scientists believe that Europa consists of a rocky core accounting for less than one-half its depth. Over this core rest many kilometers of liquid water and ice. Different models give different depths of surface ice over the ocean, and further studies of composition, salinity, and surface features will certainly lead to a better understanding, but a large saltwater ocean seems probable. Tidal forces from interactions with Jupiter and other moons would keep the water liquid despite the subfreezing exterior temperature of -170° Celsius. Craters would be eliminated whenever meteors pierced the surface ice or tidal forces formed giant cracks. Saltwater from underneath would spread out and freeze, making a new top layer in the area around the event.
Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
ADifferent models give different depths of surface ice over Europa’s ocean.
BIt is likely that Europa has a large saltwater ocean and that it will become better understood with more studies
CDifferent models of the surface ice over Europa’s large saltwater ocean have led to further studies of the ocean’s composition, salinity, and surface features
DStudies of composition, salinity, and surface features have led to a better understanding of Europa’s ocean
7
Unfortunately, Europa exploration will prove difficult. Engineers are working on plans to reach the subsurface ocean, but currently there are no workable plans to place a drill on the surface that could tunnel through many kilometers of ice. Looking at all the evidence, planetary scientists believe that Europa consists of a rocky core accounting for less than one-half its depth. Over this core rest many kilometers of liquid water and ice. Different models give different depths of surface ice over the ocean, and further studies of composition, salinity, and surface features will certainly lead to a better understanding, but a large saltwater ocean seems probable. Tidal forces from interactions with Jupiter and other moons would keep the water liquid despite the subfreezing exterior temperature of -170° Celsius. Craters would be eliminated whenever meteors pierced the surface ice or tidal forces formed giant cracks. Saltwater from underneath would spread out and freeze, making a new top layer in the area around the event.
According to paragraph 4, why is the exploration of Europa’s core unlikely?
ABecause it would require drilling through a very deep layer of surface ice
BBecause engineers have failed in attempts to place a drill on the surface
CBecause Europa’s interior consists almost entirely of a rocky core
DBecause no one is certain of the depth of Europa’s surface ice
8
The importance of liquid water to life causes astrobiologists to be very excited about Europa. Liquid water appears to be rare other than on Earth, but here we have an ocean of it. Nonetheless, a number of other considerations are important. Carbon might not be difficult to find, as long as some form of internal circulation rotates heavier metals from the rocky core out into the water. Energy might be more difficult, though. Solar radiation hits the icy surface where life is unlikely to survive. Energy would have to be generated from some other source under the ice, possibly volcanic or magnetic processes. Some astrobiologists believe that Europa could have magma vents (surface openings through which materials escape) like the deep-sea vents at the midoceanic ridges on Earth. Such vents could provide both carbon and energy for an ecosystem.
Why does the author mention the possibility of “magma vents” on Europa?
ATo question whether some form of internal circulation rotates heavier metals from the rocky core out into the water
BTo explain how Europa’s surface might be able to obtain the carbon and energy needed for an ecosystem
CTo provide a possible explanation for why much of Europa’s water remains liquid
DTo contrast energy sources on Europa with energy sources on Earth
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The importance of liquid water to life causes astrobiologists to be very excited about Europa. Liquid water appears to be rare other than on Earth, but here we have an ocean of it. Nonetheless, a number of other considerations are important. Carbon might not be difficult to find, as long as some form of internal circulation rotates heavier metals from the rocky core out into the water.[■] Energy might be more difficult, though. [■]Solar radiation hits the icy surface where life is unlikely to survive.[■] Energy would have to be generated from some other source under the ice, possibly volcanic or magnetic processes. [■]Some astrobiologists believe that Europa could have magma vents (surface openings through which materials escape) like the deep-sea vents at the midoceanic ridges on Earth. Such vents could provide both carbon and energy for an ecosystem.
Look at the four squaresthat indicate where the following sentence could be added to the passage
Thus any life present on Europa could not be powered by the Sun
Where would the sentence best fit？Click on a square sentence to the passage.
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Some scientists believe that two of Jupiter’s moons may have important preconditions for life: water and energy sources.
AThough all of Jupiter’s Galilean moons may be capable of hosting living organisms, finding evidence of life on these moons is difficult because of meteoric impacts and surface movements
BThe Galileo spacecraft showed very few large craters on Europa indicating either that it has had few large meteor impacts or that it is regularly resurfaced by flows of volcanic magma
CThe presence of internal circulation that rotates heavier metals out from its core makes it unlikely for Europa to maintain life despite the discovery of water on its surface
DThe energy produced by lo’s extensive volcanism, as well as the energy created as lo passes through Jupiter’s magnetic field, create conditions on lo’s surface that would dissolve life as we know it.
EAlthough tidal forces produced by interaction with Jupiter and other moons affect Europa much less strongly than they do lo, Europa still maintains a liquid ocean under its surface ice
FSome astrobiologists believe that Europa could have magma vents like the deep-sea vents on Earth that would provide both carbon and energy for an ecosystem under the surface ice
